Aircraft power plant



Margh 20, 1945. F. w. CALDWELL ET AL AIRCRAFT POWER PLANT Filed Aug. 19,1939 INVENTORS Eankw Caldwell 5'- Mar'ZJ'n Er] W v ATTORNEY PatentedMar. 20, 1945 AIBCBAFTPOWER PLANT Frank w. Caldwell and Eric Martin,West Hartford, Conn., assignors to United Aircraft Corflporation, EastHartford, Conn, a corporation of Delaware Application August 19, 19:9.Serial No. 291,067 1 Claim. (01. 110-1355) This invention relates toimprovements in aircraft power plants and has particular,reference to animproved mounting for an aircraft enginepropeller combination.

An object of the invention resides in the provision of an improvedaircraft power plant mounting in which the aircraft propeller and thepropeller driving engine are independently supporte by a streamlinedenclosing structure.

A furtherqibject resides in the provision of an improved aircraft powerplant mounting of the character indicated in which the engine and thepropeller are independently supported by resilient mountings and aflexible drive is provided between the engine and the propeller. l

A still further object resides'in the provision of an improved aircraftpower plant and mounting therefor in which the control devices and thepitch changing fluid for a controllable-pitch propeller are disposed ina unit with the propeller and are entirely independent of the engine.Other objects and advantages will be more particularly' pointed} outhereinafter or will become apparent as the description proceeds.

' In the accompanying drawing, in which like reference numerals are usedto designate similar r parts throughout, there is illustrated a suitablemechanical embodiment for the purpose of disclosing the invention.Thedrawin'g, however, is for the purpose of illustration only and is notto be taken as limiting the invention'since it will be apparent to thosedrilled in the art that various changes in the illustrated embodimentmay be resorted to without in any way iexceeding the scope of theinvention,

Inthe drawing, Fig. 1 is-a central longitudinal sectional view throughan aircraft power plant ofthe character indicated, the engine beingdiagrammatically illustrated only, and

Fig. 2 is a transverse sectional view of a fragmentary portion of thepower plant taken on the enclosure being tapered inwardly to provide alow air resistant streamlined form. The enclosure'or nacelle has anouter wall It and an inner wall substantially concentric with the outerwall and held in spaced relation with respect thereto by the spacers 22and through bolts 24. At its rear-. ward .end the nacelle I4 is securedto an airplane wing or fuselage, not illustrated, in a manner sumcientlystrong to support the weight of the overhanging engine and propeller.The engine is carried by end supports 26 and fl in the form of annularreinforced members mounted at their peripheryin resilientcushionelements 30 set in metal containers 32 carried by brackets flsupported'by the through bolts 24 to provide resilient connectionsbetween the end sup.- ports and the nacelle or enclosure [4, the endsupports being rigidly secured to the engine near their centers. Each ofthe end supports, 26 and 28, may conveniently comprise a substantiallycircular aperture disc 38, and annular member 38 secured to the discsurrounding the aperture and located substantially concentric of thedisc, and -a plurality of triangular-braces extending from the annularmember 38 to the periphery of the disc 36.

Both end supports are substantially similar in construction except forcertain necessary openings provided for engine accessories and the flowof cylinder cooling air, and are so disposed that the disc portions faceeach other. The reduced end portions of the engine project through theend supports and are secured to the annular members ll Y The propellerI2 is rotatably supported in a bearing 40 secured in an annular housing42 supported in the forwardportion of the enclosure l4 by suitable meanssuch as the radial brackets 44.

line 2-2- of Fig.1 looking in the direction of the y arrows.

Referring to the drawing in detail, the numeral It indicates an enginesuch as an air internal combustion engine conventionally employed forthe propulsion of aircraft and the nu-- meral l2 generally indicates acontrollable-pitch aeronautical propeller driven by. the engine II. Theengine -is surrounded and supported by a, streamlined enclosure,generally indicated at I, of circular or rounded cross section whichextends forwardly of the engine to a location adjacent to the propellerblades II, the forward portion of the The propeller is driven by meansofan extension shaft 46 operatively connected atone end to the enginethrough the vibration suppressing torque drive 4. and universal joint 50and spline drive 62 and at the other end to the propeller through theconnecting shaft 54 and reduction gear 56. The shaft. 46 may beintermediately supported by an anti-friction bearing 58 supported by theenclosure M. by the radial bracket 60. The housing 42 may convenientlysupport the propeller governor If driven from the shaft to through thegear drive l4 and a motor driven hydraulic pump 66 for supplyinghydraulic fluid under pressure to change the pitch of the propeller I!under the control of the governor 82. This pump may also furnish iiidraulic fluid under high pressure to feather and unfeather thepropeller. .The governor control may be through a hydraulic valvesomewhat schematically illustrated at I, and the feathering andunreathering of the propeller may controlled by a valve, as illustratedat 10. e housing 42 may constitute a reservoir for the hydraulic fluidused to change the pitch of the propeller and this housing together withprojecting parts or the governor 62 and motor 66 may be enclosed in asuitable sheet metal casing 12.

Certain features of the governor, its support and controlmechanism shownbut not claimed in this application are claimed in co-pending U. S.application Serial No. 333,981.

A fan or blower 14 may be mounted on the portion of the extension shaft46 between the torque drive 48 and the intermediate bearing 88 to supplycooling air to the engine. The air may be directed through a suitablefixed annular 'duct 16, which may, if desired, be provided with suitple,supposing the air Plane of a transport company to be equipped with powerunits of the type hereinabove described, by providing a few addiablepartitions for directing the air against the engine cylinders,.and the.supporting disc 38 may be provided with apertures, as indicated at 18 inFig. 2, to permit the passage oi air through the end support 28 to theengine cylinders. The

rear end support 26 is also provided with air passages, not illustrated,whichlead to the portion of the enclosure to the rear of the enginewhere suitable apertures may be provided in the enclosure to vent thecooling air from the enclosure. If desired, the cooling air may be ledfrom the support through a suitable annular duct,

as indicated at ll.

As is particularly illustrated at a: the forward portion of theenclosure I4 is drawn in closely to the propeller hub to provide anefllclent streamlined shape for the enclosure, the cooling air beingdrawn at high velocity through-the relatively narrow space between theend of the enclosure and propeller hub by the action of the blower 14.If desired, the end portion 82 may be provided with adjustable means forcontrolling the area of the air entrance space to thereby control theoperating temperature of the engine.

As stated above the double wall' enclosure i4 is rigidly secured at itsrearward end to the airplane and constitutes the sole supoprt tor theshall have sufficient structural strength to sup-.

port the engine and the propeller. a

With this arrangement the engine, the propeller and the enclosure may beformed as a unit and the enclosure may, if desired, be detachablysecured to the airplane so that one unit may be readily substituted foranother without any extensive delay in airplane operation. For exam-,tional power units the airplane could'be kept in substantiallycontinuous operation during repair or overhaul of the power plant bymerely substituting one power unit for another on an airplane. Theenclosures or nacelles may be provided with small apertures or handholes, not illustrated, to permit inspection of the power plant andminor repairs such as the changing of spark plugs.

A particularly important advantage of the illustrated arrangement is theprovision of a 'vlbra tion suppressing mounting for the engine andpropeller which is so eflective that little or no power plant vibrationis transmitted to the airplane, and' so that the engi e vibrations arenot transmitted to the prope er. By thus relieving the propeller of thestresses d to the imposition of engine vibration thereon a uch lighterand more eflicient propeller can be used. Also, by placing the reductiongear at the propeller end of the extension shaft and inserting thetorque cushion drive between the engine and the extension shaft 8. muchlighter and more flexible extension shaft can be used since the shaft isrelieved to a large extent of the eii'ect of engine .vibration and isnot subjected to the maximum torque.

While a particular mechanical embodiment has been hereinabove describedand illustrated in the accompanying drawing for the purpose of dis-,

closing theinvention, it is to be understood that the invention is notlimited to the particular arrangement so illustrated and described, butthat such changes in the size, shape and arrangements oi the variousparts may be resorted to as come within the scope of the sub-joinedclaim.

Having now described the invention so that others skilled in the art mayclearly understand the same, what it is desired to secure by LettersPatent is as follows:

An air craft, power plant-comprising, a streamlined supporting structureconstituting a complete enclosure for-said power plant, an engine, meansresilientl supporting said engine in said, enclosure, a corollable-pitch propeller operatively connected with said engine, ahousing mounted within said enclosure and rigidly connected to saidenclosure independently of said engine, said housing constituting areservoir for propeller pitch changing fluid, a propeller supportingbearing mounted within said housing, propeller control means including aspeed governor, a fluid pressure pump, and control valves forcontrolling the application of hydraulic fluid under'preasure to saidpropeller said governor, pump'and valves being mounted within saidhousing, and a flexible connection between said engine and saidpropeller.

- FRANK W. CALDWELL.

ERLE MARTIN.

